1. Field of the Invention
The invention concerns an apparatus for processing a material web comprising a stationary backing roller extending the length of the device, a working roller which can be displaced to press against the latter and has a small diameter in relation to the backing roller diameter, a pressing device by means of which the working roller can be pressed against the backing roller along a contact zone, which is continuous over the working width and allows the material web to pass through it, wherein the pressing device has a pressing body with a pressing surface, against which the working roller comes to lie on its peripheral area opposite the contact zone, and a supporting element, arranged separately form the pressing body, with a support body surface, on which the working roller comes to lie during the pressing operation. Such apparatuses are used particularly as dyeing devices for squeezing, i.e. for the dehydration and dyeing of webs saturated with dye, so-called padding machines.
2. Prior Art
An apparatus of this type is familiar from EP 0 534 930. Here both a stationary and a moving bearing bed are each provided with at least one cylindrical pressing body for the pressure application of a working roller, which is conceived as a revolving roller driven by a fixed mating roller. The stationary pressing body is a supporting body, which operates as a passive counterpressure or backing body against the pulling power exercised by the mating roller on the working roller. Such a familiar arrangement can result in disadvantageous spline effects and forces operating between the pressing/supporting bodies. The running of the working roller is impaired, and problems with reproducing working conditions can occur. The attempt has been made to counteract such disadvantageous effects by providing the beds of the bearings with elastic bolsters and deflection-controlled rollers. DE-U-296 19 695 suggests arranging the working roller so that it is displaceable in the contact position with three degrees of freedom, whereby a pressing body needs to be provided with a bearing bed with which the working roller meshes. A stationary backing or mating roller forms a drive roller to make possible the motional bearing of the pressing body in combination with the working roller. In the event of only a slight frictional force operating in the contact zone, in addition the working roller needs to be driven. Such a device achieves an automatic adjustment of the working roller to the operating conditions. In some cases, however, problems will occur with regard to reproducible processing results.
With yet another apparatus (U.S. Pat. No. 2,878,778) a web is fed between two pressure rollers. Each pressure roller is mounted on a pair of backing or mating rollers. One of the pressure rollers and the mating rollers are driven. The construction of the device is costly. The variety of rollers causes problems with regard to setting, reproducibility and cleaning.
3. Objects of the Invention
In contrast to prior art, the present invention has as its major object to alleviate said problems and to improve apparatus of the described type for processing material webs.
In particular, it is an object of the present invention to make such improvements with regard to simplicity of construction, assembly and servicability, adjustability, operational function and results, and system cleaning.